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Re: [AUDITORY] stats use in psychology and hearing science

Dr Oberfeld's post hits the nail squarely on the head; I refer readers back to the original Keppel and Wickens text known to many psychology graduates. For many people, a refresher from the textbook may be in order. - Lance Nizami PhD

From: Daniel Oberfeld <oberfeld@xxxxxxxxxxxx>
To: AUDITORY@xxxxxxxxxxxxxxx
Sent: Tuesday, June 25, 2013 12:25 AM
Subject: Re: [AUDITORY] stats use in psychology and hearing science

Dear list,

important topic! A related while probably less general problem is that data from repeated-measures / within-subjects designs (that is, when a subject is tested in more than one experimental condition) are sometimes not analyzed properly. I've seen quite a few papers in hearing science where the authors used an ANOVA for completely randomized / between-subjects design for repeated-measures data (you can spot this problem by examining the degrees-of freedom for the F-tests), or fail to use the appropriate repeated-measures ANOVA approach (e.g., apply no correction for the degrees-of-freedom when using a univariate approach).

Another point that should be considered is that while for between-subjects designs the general linear model is very robust against non-normality, this is unfortunately *not* the case for repeated-measures designs. Therefore, when analyzing non-normal data like error rates, percent correct or response times from a within-subjects design, the p-values you get from the rmANOVA could be either on the conservative or on the liberal side.

You can find an in-depth discussion of these issues in a recent paper from my lab (http://link.springer.com/article/10.3758%2Fs13428-012-0281-2).



-- PD Dr. Daniel Oberfeld-Twistel
Johannes Gutenberg - Universitaet Mainz
Department of Psychology
Experimental Psychology
Wallstrasse 3
55122 Mainz

Phone ++49 (0) 6131 39 39274
Fax  ++49 (0) 6131 39 39268